The number 35721
35721 is a perfect square (189²). Its prime factorisation is × . Divisors (21): 1, 3, 7, 9, 21, 27, 49, 63, 81, 147, 189, 243, 441, 567, 729, 1323 … 35721.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 35721: a perfect square (189²).
- 2
35721 is composite. Its prime factorisation is
- 3
The divisors add up to 62301; without 35721 itself that is 26580, so 35721 is deficient (26580 is less than 35721). Euler's totient φ(35721) = 20412 numbers up to 35721 share no factor with it.
- 4
The digits of 35721 add up to 18, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 72 steps to reach 1.
LaTeX source of the formulas on this page
\[ 35721 = 3^{6} \times 7^{2} \]35721 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 21 |
| Sum of divisors | 62301 |
| Euler totient φ(n) | 20412 |
| Square | 1275989841 |
| Cube | 45579633110361 |
| Square root | 189 |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 72 |
| Scientific notation | 3.5721 × |
| Perfect power |
35721 in other forms
| Form | Value |
|---|---|
| In words | thirty-five thousand seven hundred and twenty-one |
| Binary (base 2) | 1000101110001001 |
| Octal (base 8) | 105611 |
| Hexadecimal (base 16) | 8B89 |
| Base 3 | 1211000000 |
| As time | 35721 seconds = 9 h 55 min 21 s |
Is 35721 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | No (remainder 1) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (35721 ÷ 3 = 11907) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 1) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 1) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 3) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (35721 ÷ 7 = 5103) | A number is divisible by 7 if double the last digit and subtract it from the rest: the result is a multiple of 7. |
| 8 | No (remainder 1) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (35721 ÷ 9 = 3969) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 4) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 35721 a prime number?
No. 35721 = × , so it is divisible by 3.
What are the factors of 35721?
1, 3, 7, 9, 21, 27, 49, 63, 81, 147, 189, 243, 441, 567, 729, 1323, 1701, 3969, 5103, 11907, 35721.
What is 35721 in binary?
1000101110001001 (hexadecimal 8B89, octal 105611).
What is the square root of 35721?
189, because 189 × 189 = 35721.
Is 35721 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 35721?
35721 is a perfect square (189²).